全文获取类型
收费全文 | 31487篇 |
免费 | 1849篇 |
国内免费 | 160篇 |
专业分类
耳鼻咽喉 | 409篇 |
儿科学 | 571篇 |
妇产科学 | 647篇 |
基础医学 | 4306篇 |
口腔科学 | 1580篇 |
临床医学 | 2524篇 |
内科学 | 7966篇 |
皮肤病学 | 762篇 |
神经病学 | 2574篇 |
特种医学 | 705篇 |
外科学 | 4490篇 |
综合类 | 138篇 |
现状与发展 | 1篇 |
一般理论 | 9篇 |
预防医学 | 2640篇 |
眼科学 | 503篇 |
药学 | 1887篇 |
中国医学 | 189篇 |
肿瘤学 | 1595篇 |
出版年
2023年 | 278篇 |
2022年 | 481篇 |
2021年 | 1237篇 |
2020年 | 637篇 |
2019年 | 1072篇 |
2018年 | 1274篇 |
2017年 | 773篇 |
2016年 | 807篇 |
2015年 | 940篇 |
2014年 | 1255篇 |
2013年 | 1707篇 |
2012年 | 2617篇 |
2011年 | 2681篇 |
2010年 | 1435篇 |
2009年 | 1278篇 |
2008年 | 2010篇 |
2007年 | 2055篇 |
2006年 | 1878篇 |
2005年 | 1769篇 |
2004年 | 1433篇 |
2003年 | 1318篇 |
2002年 | 1260篇 |
2001年 | 325篇 |
2000年 | 273篇 |
1999年 | 291篇 |
1998年 | 185篇 |
1997年 | 182篇 |
1996年 | 137篇 |
1995年 | 147篇 |
1994年 | 136篇 |
1993年 | 106篇 |
1992年 | 150篇 |
1991年 | 113篇 |
1990年 | 99篇 |
1989年 | 89篇 |
1988年 | 72篇 |
1987年 | 61篇 |
1986年 | 65篇 |
1985年 | 70篇 |
1984年 | 59篇 |
1983年 | 36篇 |
1982年 | 36篇 |
1981年 | 44篇 |
1980年 | 43篇 |
1979年 | 47篇 |
1978年 | 55篇 |
1976年 | 42篇 |
1975年 | 36篇 |
1974年 | 36篇 |
1969年 | 34篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Juan M. Verdeguer M.D. Dolores Ramon M.D. Manuel Moragon M.D. Isabel Betlloch M.D. Esperanza Jorda M.D. M.D Victoria Planelles M.D. † 《Pediatric dermatology》1988,5(1):56-57
Abstract: Hydantoin is an anticonvulsant drug with several side effects. A teralogenic potential has been suggested. The fetal hydantoin syndrome is an entity that consists of a broad range of morphologic and developmental disorders in children born of epileptic mothers exposed to hydantoin during pregnancy. We treated a girl in whom onychopathy was a monosymptomatic or mild form of this syndrome. 相似文献
102.
Mehernoor F. Watcha Manuel Ramirez-Ruiz Paul F. White M. Barry Jones Richard G. Lagueruela Raghu P. Terkonda 《Journal canadien d'anesthésie》1992,39(7):649-654
Prophylactic administration of analgesics before surgery can decrease the intraoperative anaesthetic requirement and decrease pain during the early postoperative period. In a double-blind, placebo-controlled study involving 90 healthy ASA physical status I or II children undergoing bilateral myringotomy, we compared the postoperative analgesic effects of oral acetaminophen and ketorolac, when administered 30 min before induction of anaesthesia. Patients were randomized to receive saline (0.1 ml.kg-1), acetaminophen (10 mg.kg-1) or ketorolac (1 mg.kg-1) diluted in cherry syrup to a total volume of 5 ml. Anaesthesia was induced and maintained with halothane and nitrous oxide via a face mask. Postoperative pain was assessed by a blinded observer using an objective pain scale. The three study groups were similar with respect to demographic data, duration of anaesthesia and surgery, induction behaviour, oxygen saturation, incidence of postoperative emesis and, recovery times. The ketorolac group had lower postoperative pain scores and required less frequent analgesic therapy in the early postoperative period compared with the acetaminophen and placebo groups. In contrast, there were no differences in pain scores or analgesic requirements between the acetaminophen and the placebo groups. We conclude that the preoperative administration of oral ketorolac, but not acetaminophen, provided better postoperative pain control than placebo in children undergoing bilateral myringotomy. 相似文献
103.
104.
Maria Fernanda Nince Ferreira Verônica Moraes Oliveira Priscila Vieira da Cunha Osmindo Rodrigues Pires Júnior 《Toxicon》2010,55(7):1255-1262
This study evaluated the effects of [D-Leu1]Microcystin-LR variants, by the exposure of Hypophthalmichthys molitrix to Microcystis aeruginosa NPLJ4. Fish was placed in aquariums and exposed to 105 cells mL−1. For 15 days, 05 individuals were removed every 05 days, and tissue samples of liver, skeletal muscle and intestinal tract were collected for histopathologic analyses. Following exposure, those surviving were placed in clean water for 15 days to evaluate their recovery. A control without toxins was maintained in the same conditions and exhibited normal histology and no tissue damage. In exposed fish, samples were characterized by serious damages that similarly affected the different organs, such as dissociation of cells, necrosis and haemorrhage. Samples showed signs of recovery but severe damages were still observed. The results should be valuable to analyze the potency of microcystin toxicity and to help in the diagnosis of fish deaths. 相似文献
105.
Homid Fahandezh-Saddi Díaz Antonio Ríos-Luna Eduardo García-Rey Ma Jesus Rodea Butragueño Manuel Villanueva-Martinez Ma Elena Cantero-Yubero Miguel del Cerro-Gutiérrez 《European journal of orthopaedic surgery & traumatology : orthopedie traumatologie》2007,17(1):105-109
Treatment of chronic osteomyelitis of distal tibia is complex. It often requires the association of antibiotic therapy and a surgical procedure. This consists of exhaustive debridement of infected bone and soft tissue which must have adequate cutaneous coverage and vascular supply which enables creating a barrier to microorganisms and greater resistance to infection. Free or pedicled muscular flaps have been the techniques most often used for this type of lesions. Free flaps require a precise microsurgical technique and prolonged surgery. Pedicled muscular flaps do not provide sufficient coverage and vascularisation of the distal tibia for large size defects. The fasciocutaneous flap has been used for the treatment of coverage defects in the perimalleolar area and the heel. We report the utility of this flap as management of chronic osteomyelitis of the distal third of the tibia with complete healing of the infection and correct cutaneous coverage without complications. 相似文献
106.
Joaquim Ferreira MD João Maia Silva MD Rita Freire BS João Pignatelli MD Leonor Correia Guedes MD Alexandra Feijó MD Mário Miguel Rosa MD Miguel Coelho MD João Costa MD Ana Noronha BS Russell Hewett MD A. Marques Gomes PhD J.L. Cirne de Castro MD Olivier Rascol PhD Cristina Sampaio PhD 《Movement disorders》2007,22(10):1471-1475
Our objective was to evaluate the frequency of neoplastic and preneoplastic skin lesions in Parkinson's disease (PD) patients when compared with an aged-matched population. We performed a cross-sectional survey in PD patients and in an age-matched control group. Patients and controls were examined by a movement disorder specialist and a dermatologist. 150 PD patients and 146 controls were included. Thirty-five PD patients (23.3%) presented skin lesions that could be classified as neoplastic or preneoplastic vs. 20 subjects in the control group (13.7%) (OR 95%, CI 1.92 [1.05, 3.51]). However, this difference lost statistical significance when adjusted for gender (recruitment of controls was matched just for age with an over representation of males in the PD group). Twenty-nine PD patients (19%) presented actinic keratosis and basal cell carcinoma was diagnosed in 4 patients (3%). Although nonconclusive, our results are in agreement with previous studies suggesting an increased risk of skin cancer in PD patients. The frequency of actinic keratosis in PD patients and the associated risk to develop melanoma recommends its screening in future epidemiological studies. 相似文献
107.
Ultrastructural identification of oligodendrocyte/myelin proteins in corpus callosum of hypothyroid animals 总被引:1,自引:0,他引:1
A.A. Ferreira M.J.S. Pereira A.C. Manhes P.C. Barradas 《International journal of developmental neuroscience》2007,25(2):87-94
Thyroid hormone (T3) deficiency impairs the development of the CNS, particularly myelination. We have previously described an increase in the frequency of morphological abnormalities in the central myelin sheath in a hypothyroidism model, which reinforced the hypothesis of a role for T3 in myelin compaction. However, there are no data concerning the cellular distribution of myelin proteins in hypothyroid animals. In the present work, we describe the distribution of 2′,3′-cyclic nucleotide 3′-phosphodiesterase (CNPase), myelin basic protein (MBP) and proteolipid protein (PLP) throughout the central myelin sheath of a hypothyroidism model. We used euthyroid and hypothyroid adult rats at 90 days of age. In order to induce hypothyroid status, animals received 0.02% methimazol from the 19th gestation day onwards. After perfusion with a fixative mixture, small pieces of corpus callosum were obtained, dehydrated and embedded in LR White resin. Ultrathin sections were immunoreacted, using specific antibodies revealed by a secondary antibody coupled to colloidal gold particles of 10 nm. Gold particle density per region of myelin sheath for each one of these proteins was obtained. In normal animals, CNPase, PLP and MBP were identified in sites that had already been described in previous studies. In hypothyroid animals, CNPase was identified in the region corresponding to compact lamellae, which normally does not contain this protein, while, in this same region, PLP and MBP immunolabeling were decreased. These results suggest that thyroid hormone deficiency impairs the distribution of the major oligodendrocyte/myelin markers. This effect may justify the reduction in myelin sheath compaction previously demonstrated in a similar model of hypothyroidism. 相似文献
108.
Structure function interface with sequential shortening of basal and apical components of the myocardial band 总被引:1,自引:0,他引:1
Manuel Castella Gerald D. Buckberg Saleh Saleh Morteza Gharib 《European journal of cardio-thoracic surgery》2005,27(6):980-987
Objective: To mechanically test the intact cardiac structure to determine the sequence of contraction within the myocardial mass to try to explain ejection and suction. Methods: In 24 pigs (30–85 kg), segment shortening at the site of sonomicrometer crystals was continuously recorded. The ECG evaluated rhythm, and Millar pressure transducers measured intraventricular pressure and dP/dt. Results: Study of segment shortening defined a sequence of contraction within the myocardial mass, starting at the free wall of the right ventricle and on the endocardial side of the antero-septal wall of the left. Crystal location defined underlying contractile trajectory; transverse in right ventricle followed by basal posterior left ventricle, and from the endocardial anterior wall to the posterior apical segment and finally to the epicardial side of the anterior wall. Mean shortening fraction averaged 18±3%, with endocardial exceeding epicardial shortening by 5±1%. Epicardial segment crystal displacement followed endocardial shortening by 82±23 ms in the anterior wall, and finished 92±33 ms after endocardial shortening stopped, time frame that matches the interval of fast drop of ventricular pressure and the start of suction. Conclusions: Crystal shortening fraction sequence followed the rope-like myocardial band model to contradict traditional thinking, with two starting points of excitation–contraction, the right anterior free wall of the right ventricle, and the endocardial side of the anterior wall. Active suction may be due to active shortening of the epicardial fibers of the anterior wall, because relaxation was not detected when both mitral and aortic valves were closed during the interval previously termed ‘isovolumetric relaxation’. 相似文献
109.
Ana Teresa Timóteo Andreia Mamede Maria de Lurdes Ferreira José Serra José Alberto Oliveira Rui Cruz Ferreira Jorge Quininha 《Revista portuguesa de cardiologia》2007,26(2):135-143
BACKGROUND: Nitrate therapy can induce ischemic preconditioning with a consequent increase in tolerance to ischemia. In the context of acute coronary syndromes (ACS), nitrates may result in a different presentation. with greater protection. OBJECTIVES: To investigate in a population of patients with ACS whether previous chronic use of nitrates results in a different presentation of ACS. METHODS: We studied 287 patients (65 +/- 13 years, 66% male) admitted to our department in the first six months of 2005 with ACS (with and without ST-segment elevation). Of these, 8% were under nitrate therapy at the time of admission. In this group, 27% presented ACS without ST-segment elevation, while in the group without nitrates this value was 58% (p = 0.005). By univariate analysis, the use of nitrates was a predictor of the preferential occurrence of non-ST-segment elevation ACS (OR 0.27, 95% CI 0.10-0.71). After correction for the potential influence of variables (age, gender, previous revascularization and smoking) by multivariate logistic regression, nitrate therapy remained a borderline predictor of clinical presentation as non-ST-segment elevation ACS (OR 0.37, 95% CI 0.13-1.04, p = 0.059). CONCLUSIONS: Previous use of nitrates was associated with a tendency to present as non-ST-segment elevation ACS. This finding may be explained by the hypothesis that nitrates induce pharmacological preconditioning, reducing the transmural extent of myocardial infarction. 相似文献
110.
Luzitano Brando Ferreira Celso Teixeira Mendes Cludia Emília Vieira Wiezel Marcelo Rizzatti Luizon Aguinaldo Luiz Simes 《American journal of human biology》2006,18(5):702-705
Allelic frequencies of eight autosomal short‐tandem repeat (STR) loci (TH01, TPOx, CSF1PO, vWA, FES/FPS, F13A1, F13B, and CD4) were determined in 400 individuals born in the State of São Paulo. No significant deviations from Hardy‐Weinberg equilibrium were found in any loci analyzed. The Unweighted Pair‐Group Method with Arithmetic Mean (UPGMA) tree constructed based on genetic distances revealed that the present population was grouped with Europeans, and separated from African and Amerindian populations. Estimates of admixture components based on the gene identity method revealed 79% European, 14% African, and 7% Amerindian contributions to this Brazilian population sample. Am. J. Hum. Biol. 18:702–705, 2006. © 2006 Wiley‐Liss, Inc. 相似文献